Field of the Invention and Related Art Statement
The present invention concerns a floating type magnetic head and, in particular, it relates to a magnetic head having a magnetic core, in which a main magnetic circuit is constituted of an oxide magnetic material and a thin metallic magnetic layer constituting an auxiliary magnetic circuit is formed at least to the side of a magnetic gap. More in particular, it relates to a floating type magnetic head improved with bit shift.
As is well-known, the floating type magnetic head is constituted such that a disk-like magnetic recording disk (medium) is rotated and slightly floated by an air stream caused by the rotation.
FIG. 1 is a schematic view of a floating type magnetic head. A magnetic head 1 comprises a non magnetic slider 2 and a chip 3. The chip 3 is inserted in a slit 6 which is formed in an air bearing surface 4 which constitutes one of a pair of air bearing surfaces 4, 5 of the slider 2 and fixed in position by being molded with glass, for example.
Detailed structure for one embodiment of the chip 3 is shown in FIGS. 2 and 3. In FIGS. 2 and 3, a thin metallic magnetic film 11 composed of a sputtered film is formed on an I-sectioned core 10 made of oxide magnetic material e.g. Mn-Zn ferrite Reference numeral 12 denotes a C-sectioned core e.g. Mn-Zn ferrite. A pair of cores 10 and 12 are joined to each other with glass while putting the metallic magnetic film 11 therebetween so as to provide a gap G. Reference numeral 13 denotes glass. Predetermined windings are wound around the core 10 through a winding wind 14. FIG. 4B is a magnetic flux distribution diagram near the gap G in the magnetic head.
As shown in FIGS. 3 and 4B, in the head formed with the metallic magnetic film 11, magnetic fluxes are concentrated in the metallic magnetic film 11 to improve the bit shift as compared with the floating type magnetic head not formed with the magnetic film as shown in FIG. 4A (it has been found that).
However, a relationship between direction of the hard or easy magnetization axis of the thin metallic magnetic film and the bit shift has not yet been considered and the hard axis of magnetization of the thin metallic magnetic film has not been put to a specific direction in a magnetic core in which a main magnetic circuit is constituted with an oxide magnetic material, and a thin metallic magnetic film constituting an auxiliary magnetic circuit is formed at least to the side of the magnetic gap.
Japanese Patent Laid Open Sho. 63-293710 proposes a floating type magnetic head having a magnetic core prepared by vapor depositing an Fe-Al-Si type magnetic film on the surface of a substrate, in which the easy axis of magnetization of the Fe-Al-Si series magnetic film is directed substantially perpendicular to the direction of the main magnetic path. In the paper, it is described that the magnetic permeability of the metallic magnetic film is increased even if the film thickness of the metallic magnetic film is small by directing the easy axis of magnetization perpendicular to the main magnetic path. Since the main magnetic path in the paper means a magnetic flux flowing in a short circuiting manner through the gap G as shown in FIG. 5, the easy axis of magnetization aligns with the direction along the film surface of the metallic magnetic film 11 (for example, the direction of the gap depth).
Further, Japanese Patent Laid Open Sho. 62-229511 describes that the hard axis of magnetization is directed in the direction of the gap depth in a magnetic induction type thin-film magnetic head. However, the thin-film magnetic head has magnetic path constituted of only thin metallic film and, naturally, the function thereof is apparently different from that in a case of forming an auxiliary magnetic path of the metallic magnetic film. That is, in the thin-film magnetic head, as shown in FIG. 6, the metallic magnetic films 17 and 18 per se constitute a main magnetic path and the magnetic fluxes emitted from the gap form a shape of sharp loops concentrated into the magnetic metallic film. On the contrary, in a floating type magnetic head as in the present invention having a magnetic core, in which a main magnetic circuit is constituted of an oxide magnetic material and a thin metallic magnetic layer constituting an auxiliary magnetic path is formed at least on the side of a magnetic gap, the magnetic fluxes emitted from the gap form broad loops distributing to oxide cores due to magnetic flux emitted from the core, and the function of the metallic magnetic film is different from that in the thin-film magnetic head.